GR1 Titanium Tube FAQ

1. What is GR1 titanium tube?

GR1 is commercially pure titanium with 0.18% oxygen maximum. It is the softest and most formable of the pure titanium grades. Tube forms include seamless (ASTM B861) and welded (ASTM B862 and B338).

2. What is the difference between ASTM B338, B861, and B862?

B338 is for heat exchanger tubes with flattening and flaring tests. B861 is seamless pipe for general service. B862 is welded tube for general service. B338 has the tightest tolerances.

3. Which spec should I use for a heat exchanger?

Use ASTM B338 grade 1. It requires flattening and flaring tests that confirm the tube can be U-bent and expanded into a tubesheet.

4. Can I use B861 pipe for U-bend tubes?

No. B861 does not require flattening or flaring tests. The tube may crack during bending. Use B338 for U-bends.

5. What is the difference between seamless and welded tube?

Seamless has no weld seam and costs more. Welded has a longitudinal weld seam and costs 15 to 25 percent less. Both are allowed for most applications.

6. Is welded tube weaker than seamless?

Properly made welded tube has a weld strength factor of 0.85 to 1.0. For most non-critical applications, the difference is negligible. For high pressure or cyclic service, seamless is safer.

7. What is medical grade GR1?

ASTM F67 grade 1. It has tighter traceability, ISO 13485 process control, and biocompatibility testing. Industrial GR1 cannot be used for implants.

8. What is the difference between pipe and tube?

Pipe is measured by nominal size (NPS) and schedule. Tube is measured by exact outside diameter (OD). A 2 inch pipe is 60.3mm OD. A 50mm tube is exactly 50.00mm OD.

9. What are common tube sizes for heat exchangers?

19.05mm OD and 25.40mm OD are the most common. Wall thickness from 0.7mm to 2.1mm. Lengths up to 30 meters.

10. What are standard pipe sizes for general service?

NPS 1/2 to NPS 10. Schedule 5S, 10S, and 40S. OD from 21.3mm to 273mm.

11. What is the minimum bend radius for GR1 tube?

1.5 times the outside diameter. For a 19.05mm OD tube, minimum bend radius is 28.6mm. For standard production, use 2.0 x OD to reduce crack risk.

12. How long are standard tubes?

Straight tubes: 6 meters is standard. Cut lengths from 1 meter to 30 meters available. U-bent tubes: leg length specified by customer.

13. What is the chemical composition of GR1?

Titanium 99.5% minimum. Oxygen 0.18% max. Iron 0.20% max. Carbon 0.08% max. Nitrogen 0.03% max. Hydrogen 0.015% max.

14. What is the tensile strength of GR1?

240 MPa minimum. Compare to GR2 at 345 MPa and GR5 at 895 MPa.

15. What is the yield strength of GR1?

170 to 310 MPa, depending on temper. Annealed material is 170 to 240 MPa. Cold worked is 275 to 310 MPa.

16. What is the elongation of GR1?

24 percent minimum. GR2 is 20 percent. GR5 is 10 percent. This high elongation is why GR1 is used for U-bends and deep drawing.

17. What is the density of GR1?

4.51 grams per cubic centimeter. About 40 percent lighter than steel.

18. What is the hardness of GR1?

120 to 200 HV (Vickers). Similar to mild steel.

19. Can I weld GR1 tube?

Yes. Use GTAW (TIG) with ERTi-1 or ERTi-2 filler. Pure argon shielding on both sides. No post-weld heat treatment required. Weld color must be silver or light straw.

20. How do I roll GR1 tubes into a tubesheet?

Use light passes. Titanium work-hardens quickly. Test a sample first. Do not over-expand. The flaring test on the mill certificate confirms the tube can be expanded.

21. Why do my U-bend tubes crack?

Possible causes: wrong grade (GR2 or GR5 instead of GR1), bend radius too tight, weld seam on wrong side (for welded tube), or material that failed flattening test.

22. Does GR1 require post-bend heat treatment?

No. GR1 does not work-harden significantly during bending. U-bend tubes can be used as bent.